Author
Topic: How do you select the appropriate power supply for an application? (Read 2274 times)

You are given an assignment to design and build the regulated power supply (with input at 240V ac) and the Optical DetectingModule in the electronic system that will be used in a sporting goods manufacturing plant for controlling and counting thenumber of baseballs going into various sizes of boxes for shipmentThe specification given for power supply areInput voltage : 240V at 50HzRegulated Output voltage : 5.1V +/- 10%Max ripple factor : 3%Max load current : 100 mA

I think "that mad man" means LM7805 series of voltage regulators.The 78L05 is rated for 100mA, but I'd probably choose something a bit heavier if I really wanted 100mA all the time (maybe the 78M05 or 78S05 - not sure of my memory).

These days though, and to avoid regulatory (legal) hurdles it'd be well worth considering just buying an off the shelf switched-mode power-supply module (from a Chinese manufacturer) which will also be cheaper, and lighter-weight than anything you could design yourself. Well, ok, maybe for 100mA a homebrew is good enough. If you wanted a few amps then a commerical switcher is your best bet! (Probably not what the examiner was looking for.)

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